It found “systematic failures” of leadership and “grossly inadequate” security in the lead-up to the attack. It also cited “leadership and management” deficiencies, poor coordination among officials and “real confusion” in Washington and in the field over who had the authority to make decisions on policy and security concerns.

‘Very thorough’ report

Eric Boswell has resigned immediately as assistant secretary of state for diplomatic security, state department spokeswoman Victoria Nuland said in a statement. She added that Mr Boswell and the three other officials had all been put on administrative leave “pending further action”.

“The ARB (accountability review board) identified the performance of four officials, three in the bureau of the diplomatic security and one in the bureau of (near eastern) affairs,” Ms Nuland’s statement read.

Some Republicans who had criticised the Obama administration’s handling of the Benghazi attacks said they were impressed by the report. “It was very thorough,” said Senator Johnny Isakson, while Senator John Barrasso said it was “very, very critical of major failures” at high levels of the state department.

John Kerry, chair of the Senate foreign relations committee [pictured above] said: “I think that this report is going to significantly advance the security interests of those personnel and of our country.”

Hillary Clinton cleared

The Benghazi incident had appeared likely to tarnish Hillary Clinton’s four-year tenure as secretary of state but the report did not fault her specifically, finding that key decisions were made below her level.

The panel’s report and the comments by its two lead authors suggested that Ms Clinton, who accepted responsibility for the incident in a television interview about a month after the Benghazi attack, would not be held personally culpable.

Ms Clinton had been expected to appear at an open hearing on Benghazi on Thursday, but is recuperating after suffering concussion, dehydration and a stomach bug last week. She will instead be represented by her two top deputies.

Ms Clinton said in a letter accompanying the review that she would adopt all of its recommendations, which include stepping up security staffing and requesting more money to strengthen US facilities.

The national defence authorisation act for 2013, which is expected to go to Congress for final approval this week, includes a measure directing the Pentagon to increase the marine corps presence at diplomatic facilities by up to 1,000 marines.